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Home , GALEX, NGC 4414

Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association

TELESCOPE AS TIME MACHINE Read this article about NASA’s latest high-tech . Then, have fun doing one or both of the word puzzles that use the important words in the article.

A TELESCOPE FOR (ALMOST) ALL TIME Spiral have a large concentration of at the center, called the “bulge,” and “arms” that extend If all goes as planned, the National Aeronautics and outward. Viewed face on, they often look like giant pin- Space Administration (NASA) has just launched a new wheels. The spiral arms are rich in gas and dust needed to space telescope that will see back in time 80% of the way form new stars. Spiral galaxies that are sending out large to the . The Big Bang is the colossal explosion amounts of blue and light (more about this kind of that gave the its start around 12 billion years ago light later) tell scientists that a lot of new stars are forming. (give or take a few billion years). The Evolution Our galaxy, the Milky Way, is an average-sized, spiral- Explorer, or GALEX for short, is an -orbiting telescope shaped galaxy and is forming new stars at a rate of one that is looking back 10 billion years to help scientists under- like our Sun every year. stand how galaxies like our Milky Way came to be and how they have changed over cosmic time. During its 29-month mission, GALEX will survey nearly the entire sky and gather galactic light that has been journeying toward us for nearly the entire history of the universe.

Some different types of spiral galaxies.

The Galaxy Evolution This magnificent Explorer (GALEX) , orbiting space telescope photographed by the will look back in time 10 Hubble Space billion years. Telescope, is called NGC 4414. It is about 60 million light-years away.

Elliptical galaxies range from spherical to cigar- shaped. These galaxies don’t contain much gas, so are GALAXIES 101 rarely seen to be forming new stars. Their red color tells scientists that they contain mostly old stars. Irregular Galaxies are clusters of gas, dust, many different galaxies don’t have much structure and are generally types of stars in all different phases of their life cycles, and smaller than spiral or elliptical galaxies. various strange objects such as black holes. Our own Milky Way galaxy contains over 200 billion stars, and the entire universe probably contains over 100 billion galaxies. Galaxies come in a huge variety of shapes and sizes. Dwarf galaxies may contain as few as 10 million stars, while massive galaxies may have a trillion (that’s a thousand billion) stars. Shapes of galaxies may be spiral, elliptical, or irregular. Some different types of elliptical and irregular galaxies.

1 Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association

have traveled. GALEX is able to detect light that is ex- tremely old, extremely red-shifted.

The shape of this Like the that has given us so formerly spiral galaxy, many awesome pictures of the universe, GALEX operates called NGC 6745, has above Earth’s atmosphere, so gathers light that cannot been distorted as it collides with another penetrate to telescopes on Earth’s surface. While the galaxy. Hubble is used by many astronomers around the world to study very particular, tiny regions of the sky, GALEX has its very specific mission to look at nearly the whole sky, a goodly piece at a time. With the “all-sky survey” GALEX is making, scientists will be able to see how galaxies in the early universe (far, BEYOND IMAGINATION’S LIMITS far away) are different from galaxies of more recent times (relatively nearby). Because distant galaxies appear to us So how is looking at far away galaxies like looking as they were millions or even billions of years ago, we can back in time? At 300,000 kilometers per second (186,000 study how they evolve. We see what they looked like when miles per second), nothing travels faster than light. Even at the universe was much younger, as galaxies were first this speed, though, it still takes time for light to get from one forming. As we look at closer and closer galaxies we see place to another. If you are looking at your girlfriend just how they change as they age, just as looking at babies, across the classroom, you are seeing her as she was a tiny children, teenagers, and then adults can show how we fraction of a second ago, rather than as she looks right now. humans change as we age. It takes about 8 minutes for light from the Sun to reach Earth. The spacecraft, which NASA launched back in 1977, is now the farthest human-made object from MORE VIOLET THAN VIOLET? Earth. Even though this spacecraft is still inside our GALEX is paying particular attention to how the system, its signal, traveling at light speed, takes 12 hours to universe looks in ultraviolet (UV) light. UV light waves are reach Earth! not visible to humans. The shortest light waves that humans So, if Voyager’s signal takes that long to reach us, you can see are blue or violet. Ultraviolet waves, as their can begin to imagine how long it takes light to reach us from names implies, are shorter than violet waves. These shorter far distant galaxies. What we are seeing of those galaxies waves carry more energy than do visible light waves (or the is not how they look today, but how they looked when that light waves that are longer than those we can see, like now-very-old light left them, thousands or millions or billions infrared and radio waves). Most of the UV light from the of years ago. Sun is absorbed or scattered by Earth’s atmosphere, but what does get through to Earth’s surface is what causes DOES THE LIGHT SHOW ITS AGE? fair-skinned people to get sunburned. How will scientists know how old the light is that GALEX is receiving? Scientists know that the universe is expanding. Like a chocolate chip cake in the oven, space is the “cake batter” that keeps getting bigger and bigger, while the stars and galaxies are the “chocolate chips” that keep getting farther and farther apart. Like energy pulsing through the ocean, GALEX detects ultraviolet objects in the sky that are light energy travels in waves. As light waves travel through more than a million times fainter than objects we can see in this expanding space, they get stretched out. The longer visible light from even the darkest locations on the ground. they spend traveling through space, the more stretched out What is so special about UV in studying stars and they get. Because red light waves are longer than the light galaxies? The youngest stars are the brightest and hottest waves of other visible colors, scientists say that light coming stars, and they produce a lot of UV light. By precisely from distant stars and galaxies is “red-shifted.” The more measuring the brightness of the UV light coming from a red-shifted the light waves, the farther (and longer) they galaxy, scientists can tell how fast that galaxy is churning

2 Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association out new stars. GALEX’s UV surveys will help scientists DISCUSSION measure not only rates, but many other characteristics of galaxies, such as luminosity (brightness), The starship Cosmographer receives a distress shape, gas content, how galaxies cluster together, and how signal. Zorp, the communication officer, announces it is such properties change over cosmic time. coming from an ally’s damaged ship four light years away. How might Zorp know the distance to the source of the We may not be able to actually place ourselves into signal? Should the crew just drop everything and rush to the past, but remember: Space is time and time is space. the aid of the ship in distress? Why or why not? What So to look far back in time, all you need is a good telescope! would have to be different from our current understanding of science for the Cosmographer to get to the damaged GALACTIC PUZZLES ship on time to save its crew? Now, test your galactic IQ by solving one or both of these word puzzles. But don’t cheat! If you do both puzzles, do the crossword first.

EXPLORING THE GALAXIES

17 Light gets under your skin 19 The youngest and the _____ 21 Like air out in space 24 Amoeba-like galaxy 26 Pinwheel galaxy 29 From where we stand 30 Our closest celestial family 33 How much it shines 35 Much stranger than that of Alice’s rabbit 36 More than blue

Down 2 True nothingness 4 Space agency of the U.S. 5 Make longer 8 What started the whole thing 10 Opposite of contracting 11 A red star is this 13 A blue star is this 14 Raw material for new stars 15 Light made longer 18 Change over time 20 Age of the universe, times about 12 years 22 Great balls of fire 23 Star student 25 Egg-shaped galaxy Across 27 The farthest artifact 28 Surveying the galaxies 1 All there is 31 Speediest traveler 3 Nearby star 32 Pulse of energy 6 Common to human, octopus, and some galaxies 34 Lots made where stars are born, abbrevia- 7 Viewer into the past tion 9 The blanket above us 12 Our galactic home 16 Another eye in the sky Puzzle solution on Page 5.

3 Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association

The words in the list on the left are hidden in the jumble of letters. Words may be frontwards, backwards, upside-down, or diagonal. When you find a word, draw a box around it and cross it off the list.

This article was written by Diane Fisher, writer and designer of The Space Place website at spaceplace..gov. The article was provided through the courtesy of the Jet Propulsion Laboratory, Califor- nia Institute of Technology, Pasadena, California, under a contract with the National Aeronautics and Space Administration. Puzzle solution on Page 5.

4 Originally published in The Technology Teacher, May/June 2003, by the International Technology Education Association

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